A high-temperature impact wear-resistant reinforced layer, a preparation method and application thereof

Abstract

The present application relates to a kind of high-temperature impact wear strengthening layer and its preparation method and application, belong to laser processing material technical field.High-temperature impact wear strengthening layer is prepared using high carbide content alloy powder, the high carbide content alloy powder is in mass percentage, chemical composition is as follows:Al:2.7%~3.0%, C:5.8%~6.3%, Cr:63.5%~64.5%, B:0.02%~0.04%, O≤200ppm, N≤50ppm, H≤5ppm, the balance is Ni.The strengthening layer of the present application, high hardness, high-temperature impact wear resistance is good, can satisfy the demand of the surface performance of heavy-duty diesel engine key component.

Description

Technical Field

[0001] This invention relates to the field of laser processing materials technology, and in particular to a high-temperature impact and wear resistant reinforcing layer, its preparation method, and its application. Background Technology

[0002] Heavy-duty diesel engines are characterized by high mechanical loads, high thermal loads, and low emissions, resulting in extremely harsh operating conditions for the valve-valve seat friction pair. The valve seat is the most crucial component of the diesel engine's intake and exhaust system. Located on the cylinder head, it forms a friction pair with the valve, fulfilling functions such as intake and exhaust organization, combustion gas sealing, and valve heat transfer. Traditionally, valve seats are made of high-temperature and wear-resistant materials (e.g., cemented carbide) and are interference-fitted onto the cylinder head. However, for heavy-duty diesel engines with high thermal loads and compact cylinder head structures, there is insufficient space to accommodate embedded valve seats. Therefore, valve seat bores with surface-reinforced treatment of the cylinder head material are used to achieve a valve-valve seat bore mating friction pair.

[0003] In existing technologies, localized induction hardening of the cylinder head material is often used to achieve surface hardening of the valve seat bores. However, due to the high temperatures in the valve seat bores of heavy-duty diesel engines, the valves constantly impact these bores, leading to severe high-temperature wear. This results in valve seal failure and excessive valve sagging, significantly impacting the engine's performance and service life. Therefore, there is an urgent need to develop new technologies for strengthening the valve seat bores in integrated cylinder heads for heavy-duty diesel engines. Summary of the Invention

[0004] Based on the above analysis, the present invention aims to provide a high-temperature impact wear resistant reinforcing layer, its preparation method and application, in order to solve the problem of poor high-temperature impact wear resistance of existing valve seat bores.

[0005] The objective of this invention is mainly achieved through the following technical solutions:

[0006] This invention provides a high-temperature impact and wear resistant reinforcing layer, which is prepared from alloy powder with high carbide content. The chemical composition of the high carbide content alloy powder, by mass percentage, is: Al: 2.7%–3.0%, C: 5.8%–6.3%, Cr: 63.5%–64.5%, B: 0.02%–0.04%, O≤200ppm, N≤50ppm, H≤5ppm, with the balance being Ni.

[0007] Furthermore, the microstructure of the alloy powder with high carbide content includes Ni3Al phase, a small amount of γ-Ni phase and carbides. The structure of the carbides mainly includes Cr7C3, and the mass content of the carbides is 63% to 67%.

[0008] Furthermore, the ratio of nickel equivalent to aluminum equivalent in the high carbide content alloy powder is 3.2 to 3.5.

[0009] Furthermore, the alloy powder with high carbide content has the following chemical composition by mass percentage: Al: 2.75%–2.95%, C: 5.82%–6.28%, Cr: 63.5%–64.5%, B: 0.02%–0.035%, O≤190ppm, N≤45ppm, H≤5ppm, with the balance being Ni.

[0010] The present invention also provides a method for preparing the above-mentioned high-temperature impact and wear resistant reinforcing layer, comprising the following steps:

[0011] Step 1: High carbide content alloy powder is conveyed to the substrate surface using a coaxial powder feeding method;

[0012] Step 2: Use laser cladding to clad alloy powder with high carbide content onto the substrate surface to form a reinforcing layer.

[0013] Furthermore, in step 1, the particle size range of the intermetallic compound alloy powder with high carbide content is controlled to be 53 μm to 124 μm.

[0014] Furthermore, in step 1, the coaxial powder feeding rate is controlled to be 10g / min to 20g / min.

[0015] Furthermore, in step 2, the power of the laser cladding is controlled to be 2200W to 2400W, and the scanning speed is 0.36m / min to 0.60m / min.

[0016] The present invention also provides an application of a high-temperature impact and wear resistant reinforcing layer, wherein the high-temperature impact and wear resistant reinforcing layer is used for surface modification of diesel engine components.

[0017] The present invention also provides a diesel engine cylinder head, wherein the valve seat bore of the diesel engine cylinder head includes the above-mentioned high-temperature impact and wear resistant reinforcing layer.

[0018] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0019] 1) The high-temperature impact and wear resistant reinforcing layer of the present invention is prepared by alloy powder with high carbide content. The alloy powder with high carbide content has a high content of carbide reinforcing phase. The reinforcing layer prepared by the alloy powder with high carbide content of the present invention has high hardness and good wear resistance.

[0020] 2) The high carbide content alloy powder used in the preparation of the high-temperature impact and wear resistant strengthening layer of the present invention has a high nickel to aluminum equivalent atomic ratio, which reduces the cracking tendency of the strengthening layer. The Ni3Al-based alloy strengthening layer prepared on the surface of the parts has a dense structure, high bonding strength with the matrix, and good wear resistance, which can meet the surface performance requirements of key components in application environments such as high load impact and high temperature wear resistance.

[0021] 3) In the method for preparing the high-temperature impact and wear resistant reinforcing layer of the present invention, by precisely controlling the power and scanning speed of laser cladding, it is ensured that when the reinforcing layer is prepared by laser cladding technology, the carbide melts and is re-formed in situ, which can reduce the size of the carbide and make the carbide more uniformly distributed in the reinforcing layer.

[0022] 4) The valve seat bore of the diesel engine cylinder head of the present invention includes the above-mentioned high-temperature impact wear resistant reinforcing layer, the average hardness of the reinforcing layer is 1000-1200 HV, and the wear rate is ≤0.6×10 -5 mm 3 The shear strength of the interface between the aforementioned reinforced layer and the cylinder head substrate is 400–500 MPa, and the average oxidation rate at 1000℃ is ≤0.06 g / (m). 2 ·h), compared with the surface-hardened valve seat bore, the wear of the valve seat bore of the diesel engine cylinder head of the present invention is reduced by more than 60% (e.g., 61% to 86%).

[0023] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description and the accompanying drawings. Attached Figure Description

[0024] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0025] Figure 1 This is a schematic diagram showing the location of the high-temperature impact wear resistant reinforcement layer of the valve seat bore in the diesel engine cylinder head of Example 1;

[0026] Figure 2 This is a macroscopic schematic diagram of the valve seat bore with a high-temperature impact and wear resistant reinforcement layer in Example 1;

[0027] Figure 3 This is a topographic image of the high-temperature impact and wear resistant reinforcement layer of the valve seat bore in Example 1.

[0028] Figure label:

[0029] 1-High temperature impact and wear resistant reinforcement layer. Detailed Implementation

[0030] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of the present invention and, together with the embodiments of the present invention, serve to illustrate the principles of the present invention.

[0031] This invention provides a high-temperature impact and wear resistant reinforcing layer, which is prepared from alloy powder with high carbide content. The alloy powder with high carbide content has the following chemical composition by mass percentage: Al: 2.7%–3.0%, C: 5.8%–6.3%, Cr: 63.5%–64.5%, B: 0.02%–0.04%, O≤200ppm, N≤50ppm, H≤5ppm, with the balance being Ni. The microstructure of the alloy powder with high carbide content includes Ni3Al phase, a small amount of γ-Ni phase, and carbides. The structure of the carbides mainly includes Cr7C3, with a mass content of 63%–67% and a mass content of 2.0%–5.0% for the γ-Ni phase. The carbides are dispersed and have a length of 10μm–20μm.

[0032] The high-temperature impact and wear resistant reinforcing layer of the present invention is prepared from alloy powder with high carbide content. The high carbide content in the alloy powder can significantly improve the hardness of the high-temperature impact and wear resistant reinforcing layer, thereby improving the hardness of the reinforcing layer prepared with the alloy powder, and providing a basis for the reinforcing layer to obtain good high-temperature impact and wear resistance.

[0033] Specifically, considering that the carbide content in the high carbide content alloy powder of the present invention is 63% to 67%, when using it to prepare a high-temperature impact wear resistant reinforcing layer, the high carbide ratio will lead to a greater tendency for cladding defects such as cracks. Therefore, the atomic ratio of nickel equivalent to aluminum equivalent in the high carbide content alloy powder of the present invention is controlled to be 3.2 to 3.5. By increasing the atomic ratio of nickel and aluminum equivalent, the formation of hardened NiAl phase can be suppressed, ensuring that the base phase of the reinforcing layer is Ni3Al phase and γ solid solution phase, thereby improving the plasticity of the base phase of the reinforcing layer and suppressing the formation of cladding defects.

[0034] Specifically, in this invention, the inventors, through in-depth research, proposed the following principle for calculating the number of nickel equivalent atoms:

[0035]

[0036] Where Ni represents the mass percentage of Ni element in the alloy powder with high carbide content, and Cr... Ni3Al溶 It ranges from 3% to 7%.

[0037] The principle for calculating the equivalent atomic number of aluminum is as follows:

[0038]

[0039] Where Al represents the mass percentage of Al element in alloy powder with high carbide content, and Cr... Ni3Al溶 It ranges from 3% to 7%.

[0040] Specifically, as a preferred embodiment, the mass percentage of each component in the high carbide content alloy powder of the present invention is as follows: Al: 2.75% to 2.95%, C: 5.82% to 6.28%, Cr: 63.5% to 64.5%, B: 0.02% to 0.035%, O ≤ 190 ppm, N ≤ 45 ppm, H ≤ 5 ppm, with the balance being Ni.

[0041] It should be noted that the high carbide content alloy powder of the present invention contains a relatively large amount of Ni3Al, which exhibits room temperature brittleness. A small amount of boron (B) can improve the room temperature ductility of Ni3Al and inhibit crack formation. However, when B is excessive, it accumulates at the grain boundaries, promoting the formation of hot cracks. Within the chemical composition range of the high carbide content alloy powder of the present invention, when the B content is below 0.02%, it cannot improve the plasticity of Ni3Al, while when the B content is above 0.04%, the strengthening layer has a greater tendency to hot crack. Therefore, the B content of the present invention is determined to be 0.02% to 0.04%, which not only ensures the room temperature ductility of the strengthening layer but also inhibits the formation of hot cracks.

[0042] It should be noted that during the laser cladding process for preparing the reinforced layer using the high carbide content alloy powder of this invention, impurity elements such as O, H, and N will participate in the metallurgical reaction. Excessive O content can easily lead to fatigue problems and increased wear; excessive N content can easily lead to AlN formation and increased cracking tendency; excessive H content increases the brittleness of the reinforced layer. Therefore, this invention controls O ≤ 200 ppm, N ≤ 50 ppm, and H ≤ 5 ppm.

[0043] This invention also provides a method for preparing a high-temperature impact and wear resistant reinforcing layer, comprising the following steps:

[0044] Step 1: The alloy powder with high carbide content is transported to the surface of the substrate using a coaxial powder feeding method;

[0045] Step 2: Use laser cladding to clad alloy powder with high carbide content onto the substrate surface to form a high-temperature impact and wear resistant reinforcement layer.

[0046] Specifically, in step 1 above, considering that if the particle size of the alloy powder is too large, unmelted powder will appear during laser cladding, while if the particle size is too small, it will easily rub against the powder feeding equipment during the laser cladding process, causing blockage. Therefore, the particle size range of the high carbide content intermetallic compound alloy powder of this invention is controlled to be 53μm to 124μm.

[0047] Specifically, in step 1 above, considering that when the powder feed rate is low, the dilution rate of the matrix (e.g., steel material) is high, and the hardness and wear resistance of the reinforcing layer decrease significantly; when the powder feed rate is high, the dilution rate of the matrix is ​​low, the metallurgical bonding between the reinforcing layer and the matrix is ​​insufficient, and unmelted powder may also appear. Therefore, the coaxial powder feed rate is controlled at 10 g / min to 15 g / min.

[0048] Specifically, in step 2 above, considering the high carbide content in the alloy powder of this invention, if the laser cladding power is too low or the scanning speed is too high, some powder may not melt completely, resulting in unmelted material in the reinforcing layer and poor adhesion between the reinforcing layer and the substrate. Therefore, after in-depth research, the inventors controlled the laser cladding power to be 2200W to 2400W and the scanning speed to be 0.36m / min to 0.60m / min.

[0049] Specifically, in step 2 above, in the laser cladding method, the laser beam is a circular spot or a rectangular spot; the diameter of the circular spot is 4-5 mm, the length of the rectangular spot is 4-6 mm, and the width is 2-5 mm.

[0050] It should be noted that when using laser cladding technology to prepare the reinforcing layer, the carbides (mainly including Cr7C3) melt and then re-form in situ, which can reduce the size of the carbides and make the carbides more evenly distributed in the reinforcing layer.

[0051] The present invention also provides an application of a high-temperature impact and wear resistant reinforcing layer, which can be used for surface modification of diesel engine (e.g., heavy-duty diesel engine) components.

[0052] The present invention also provides a diesel engine cylinder head, wherein the valve seat bore of the diesel engine cylinder head includes the above-mentioned high-temperature impact and wear resistant reinforcing layer.

[0053] The present invention also provides a method for preparing a diesel engine cylinder head, comprising the following steps:

[0054] S1. A groove is machined at the valve seat hole of the integrated cylinder head;

[0055] S2. The alloy powder with high carbide content is conveyed to the groove of the valve seat hole by coaxial powder feeding method.

[0056] S3. Using laser cladding, alloy powder with high carbide content is clad onto the groove to form a high-temperature impact and wear resistant strengthening layer.

[0057] S4. Machin the valve seat bore area with the high-temperature impact and wear resistant reinforcement layer to the finished size.

[0058] Specifically, in S3 above, the thickness of the reinforcing layer is 1.5mm to 2.0mm.

[0059] Specifically, the structure of the aforementioned reinforced layer includes Ni3Al phase, carbides, and a small amount of γ-Ni phase. The carbides are dispersed in the Ni3Al phase. The carbides mainly include Cr7C3 carbides. The mass content of the γ-Ni phase is 2.0% to 5.0%, the mass content of the carbides is 60% to 70%, and the size of the carbides is 2μm to 5μm.

[0060] Specifically, the average hardness of the aforementioned reinforced layer is 1000–1200 HV (e.g., 1040–1190 HV), and the wear rate is ≤0.6×10⁻⁶. -5 mm 3 / (N·m)(e.g., 0.3×10) -5 ~0.52×10 -5 mm 3 The shear strength of the interface between the aforementioned reinforced layer and the cylinder head substrate is 400–500 MPa, and the average oxidation rate at 1000℃ is ≤0.06 g / (m³). 2 •h)(e.g. 0.02~0.035g / (m 2 ·h)).

[0061] The following detailed description of preferred embodiments of the present invention illustrates the principles of the invention and is not intended to limit the scope of the invention.

[0062] Example 1

[0063] This embodiment provides a high-temperature impact and wear resistant reinforcing layer, a diesel engine cylinder head, and a method for preparing the same.

[0064] The high-temperature impact wear resistant reinforcing layer in this embodiment is prepared using alloy powder with high carbide content. The chemical composition of the high-carbide content alloy powder, by mass percentage, is: Al 2.87%, C 6.05%, Cr 64.46%, B 0.03%, O 153ppm, N 35ppm, H 3ppm, with the balance being Ni. The atomic ratio of nickel equivalent to aluminum equivalent is approximately 3.24. The microstructure of the high-carbide content alloy powder includes Ni3Al phase, a small amount of γ-Ni phase, and carbides. The carbide structure mainly consists of Cr7C3, with a carbide mass content of approximately 65% ​​and the γ-Ni phase mass content of approximately 2.5%. The carbides are dispersed, with a length of 10μm to 20μm. The particle size range of the high-carbide content alloy powder is 55μm to 110μm.

[0065] The diesel engine cylinder head of this embodiment includes the aforementioned high-temperature impact and wear resistant reinforcing layer. The method for preparing the diesel engine cylinder head includes:

[0066] S1. A groove that meets the product requirements is machined at the valve seat hole of the integrated cylinder head;

[0067] S2. The alloy powder with high carbide content is conveyed to the groove of the valve seat hole by coaxial powder feeding method.

[0068] S3. Using laser cladding, alloy powder with high carbide content is clad onto the groove to form a high-temperature impact and wear resistant strengthening layer 1; the laser power is 2200W, the scanning speed is 0.36m / min, the laser rectangular spot size is 5mm×2mm, and the coaxial powder feeding rate is 12.5g / min.

[0069] S4. Machin the valve seat bore area with the high-temperature impact and wear resistant reinforcement layer to the finished size.

[0070] Specifically, in S3 above, the thickness of the reinforcing layer is 2.0 mm.

[0071] Figure 1 The diagram shown is a schematic representation of the location of the high-temperature impact wear resistant reinforcement layer in the valve seat bore of the diesel engine cylinder head in this embodiment. Figure 2 This is a macroscopic schematic diagram of a valve seat bore with a high-temperature impact and wear resistant reinforcement layer; Figure 3 Morphology of the high-temperature impact and wear-resistant reinforcement layer of the valve seat bore.

[0072] Specifically, the microstructure of the aforementioned reinforced layer includes Ni3Al phase, carbides, and a small amount of γ-Ni phase, with the carbides dispersed in the Ni3Al phase. The carbides mainly consist of Cr7C3 carbides, with the γ-Ni phase accounting for approximately 2.4% by mass and the carbides accounting for approximately 66% by mass. The carbide size ranges from 2 μm to 5 μm. The aforementioned reinforced layer is free of defects such as cracks and pores, has a dense microstructure, and exhibits uniform carbide distribution.

[0073] Specifically, the average hardness of the aforementioned reinforced layer is 1127 HV, and the shear strength of the interface between the reinforced layer and the cylinder head substrate is 483 MPa. Under dry friction conditions (surface friction, with Ni80 nickel-chromium alloy as the grinding material), the wear rate of the reinforced layer is 0.38 × 10⁻⁶. -5 mm 3 / (N·m), average oxidation rate at 1000℃ is 0.023 g / (m 2 ·h).

[0074] In this embodiment, the valve seat bore of the cylinder head and the Ni80 nickel-chromium alloy valve form a valve-valve seat bore friction pair. Bench tests showed that, compared to surface-hardened valve seat bores, the wear of the valve seat bore in this embodiment was reduced by approximately 86%.

[0075] Example 2

[0076] This embodiment provides a high-temperature impact and wear resistant reinforcing layer, a diesel engine cylinder head, and a method for preparing the same.

[0077] The high-temperature impact wear resistant reinforcing layer in this embodiment is prepared using alloy powder with high carbide content. The chemical composition of the high-carbide content alloy powder, by mass percentage, is: Al 2.79%, C 5.87%, Cr 63.92%, B 0.025%, O 178ppm, N 41ppm, H 4ppm, with the balance being Ni. The atomic ratio of nickel equivalent to aluminum equivalent is approximately 3.40. The microstructure of the high-carbide content alloy powder includes Ni3Al phase, a small amount of γ-Ni phase, and carbides. The carbide structure mainly consists of Cr7C3, with a carbide mass content of 64% and the γ-Ni phase mass content of approximately 4.0%. The carbides are dispersed, with a length of 11μm to 20μm. The particle size range of the high-carbide content alloy powder is 65μm to 114μm.

[0078] The diesel engine cylinder head of this embodiment includes the aforementioned high-temperature impact and wear resistant reinforcing layer. The method for preparing the diesel engine cylinder head includes:

[0079] S1. A groove that meets the product requirements is machined at the valve seat hole of the integrated cylinder head;

[0080] S2. The alloy powder with high carbide content is conveyed to the groove of the valve seat hole by coaxial powder feeding method.

[0081] S3. Using laser cladding, alloy powder with high carbide content is clad onto the groove to form a high-temperature impact and wear resistant strengthening layer 1; the laser power is 2350W, the scanning speed is 0.60m / min, the laser rectangular spot size is 5mm×5mm, and the coaxial powder feeding rate is 15g / min.

[0082] S4. Machin the valve seat bore area with the high-temperature impact and wear resistant reinforcement layer to the finished size.

[0083] Specifically, in S3 above, the thickness of the reinforcing layer is 1.8 mm.

[0084] Specifically, the microstructure of the aforementioned reinforced layer includes a Ni3Al phase, carbides, and a small amount of γ-Ni phase. The carbides are dispersed in the Ni3Al phase. The carbides mainly consist of Cr7C3 carbides, with a γ-Ni phase content of 3.8% by mass and carbides accounting for approximately 63% by mass. The carbide size ranges from 2 μm to 5 μm. The reinforced layer is free of defects such as cracks and pores, has a dense microstructure, and exhibits uniform carbide distribution.

[0085] Specifically, the average hardness of the aforementioned reinforced layer is 1045 HV, and the shear strength of the interface between the reinforced layer and the cylinder head substrate is 457 MPa. Under dry friction conditions (surface friction, with Ni80 nickel-chromium alloy as the grinding material), the wear rate of the reinforced layer is 0.52 × 10⁻⁶. -5 mm 3 / (N·m), average oxidation rate at 1000℃ is 0.034 g / (m 2 ·h).

[0086] In this embodiment, the valve seat bore of the cylinder head and the Ni80 nickel-chromium alloy valve form a valve-valve seat bore friction pair. Bench tests showed that, compared to surface-hardened valve seat bores, the wear of the valve seat bore in this embodiment was reduced by approximately 61%.

[0087] Example 3

[0088] This embodiment provides a high-temperature impact and wear resistant reinforcing layer, a diesel engine cylinder head, and a method for preparing the same.

[0089] The high-temperature impact wear resistant reinforcing layer in this embodiment is prepared using alloy powder with high carbide content. The chemical composition of the high-carbide content alloy powder, by mass percentage, is: Al 2.85%, C 6.13%, Cr 64.37%, B 0.03%, O 139ppm, N 27ppm, H 3ppm, with the balance being Ni. The atomic ratio of nickel equivalent to aluminum equivalent is approximately 3.26. The microstructure of the high-carbide content alloy powder includes Ni3Al phase, a small amount of γ-Ni phase, and carbides. The carbide structure mainly consists of Cr7C3, with a carbide mass content of approximately 65% ​​and the γ-Ni phase mass content of approximately 2.9%. The carbides are dispersed, with a length of 11μm to 20μm. The particle size range of the high-carbide content alloy powder is 58μm to 112μm.

[0090] The diesel engine cylinder head of this embodiment includes the aforementioned high-temperature impact and wear resistant reinforcing layer. The method for preparing the diesel engine cylinder head includes:

[0091] S1. A groove that meets the product requirements is machined at the valve seat hole of the integrated cylinder head;

[0092] S2. The alloy powder with high carbide content is conveyed to the groove of the valve seat hole by coaxial powder feeding method.

[0093] S3. Using laser cladding, alloy powder with high carbide content is clad onto the groove to form a high-temperature impact and wear resistant strengthening layer 1; the laser power is 2200W, the scanning speed is 0.48m / min, the laser rectangular spot size is 5mm×2mm, and the coaxial powder feeding rate is 10g / min.

[0094] S4. Machin the valve seat bore area with the high-temperature impact and wear resistant reinforcement layer to the finished size.

[0095] Specifically, in S3 above, the thickness of the reinforcing layer is 1.6 mm.

[0096] Specifically, the microstructure of the aforementioned reinforced layer comprises Ni3Al phase, carbides, and a small amount of γ-Ni phase, with the carbides dispersed in the Ni3Al phase. The carbides mainly consist of Cr7C3 carbides, with the γ-Ni phase comprising approximately 2.8% by mass and the carbides comprising approximately 64.5% by mass. The carbide size ranges from 2 μm to 5 μm. This reinforced layer is free of defects such as cracks and pores, exhibits a dense microstructure, and has a uniform distribution of carbides.

[0097] Specifically, the average hardness of the aforementioned reinforced layer is 1076 HV, and the shear strength of the interface between the reinforced layer and the cylinder head substrate is 462 MPa. Under dry friction conditions (surface friction, with Ni80 nickel-chromium alloy as the grinding material), the wear rate of the reinforced layer is 0.43 × 10⁻⁶. -5 mm3 / (N·m), average oxidation rate at 1000℃ is 0.029 g / (m 2 ·h).

[0098] In this embodiment, the valve seat bore of the cylinder head and the Ni80 nickel-chromium alloy valve form a valve-valve seat bore friction pair. Bench tests showed that, compared to surface-hardened valve seat bores, the wear of the valve seat bore in this embodiment is reduced by approximately 74%.

[0099] Comparative Example 1

[0100] This comparative example provides a reinforcing layer and its preparation method.

[0101] The reinforcing layer in this comparative example was prepared using alloy powder with high carbide content. The chemical composition of the alloy powder with high carbide content, by mass percentage, was: Al: 5.49%, C: 4.25%, Cr: 45.41%, B: 0.023%, O: 162ppm, N: 33ppm, H: 4ppm, with the balance being Ni. The atomic ratio of nickel equivalent to aluminum equivalent in the alloy powder was approximately 3, and the carbide content in the alloy powder was approximately 45%.

[0102] The alloy powder with high carbide content was used to perform laser cladding on the surface of 42CrMo. The laser power was 2400W, the scanning speed was 0.17m / min, the diameter of the laser circular spot was 3mm, and the coaxial powder feed rate was 15g / min, forming an in-situ self-generated carbide reinforced alloy strengthening layer.

[0103] The comparative example has a relatively low number of nickel and aluminum equivalent atoms, and the reinforcement layer has cracks.

[0104] Comparative Example 2

[0105] This comparative example provides a reinforcing layer and its preparation method.

[0106] The chemical composition of the alloy powder used to prepare the reinforcing layer in this comparative example is the same as that in Example 1, by mass percentage.

[0107] The alloy powder with high carbide content was used to perform laser cladding on the surface of 45 steel. The laser power was 1600W, the scanning speed was 0.13m / min, the laser rectangular spot size was 5×2mm, and the coaxial powder feed rate was 20g / min, forming an in-situ self-generated carbide reinforced alloy strengthening layer.

[0108] In this comparative example, the reinforcing layer contains unmelted powder, the bonding force between the reinforcing layer and the substrate is low, and the shear strength of the interface between the reinforcing layer and the substrate is 187 MPa.

[0109] Comparative Example 3

[0110] This comparative example provides a reinforcing layer and its preparation method.

[0111] The alloy powder used to prepare the reinforcing layer in this comparative example, by mass percentage, has the following composition: Al: 9.22%, C: 1.35%, Cr: 19.01%, B: 0.06%, O: 146ppm, N: 25ppm, H: 3ppm, with the balance being Ni. The atomic ratio of nickel equivalent to aluminum equivalent is approximately 3, and the mass content of in-situ self-generated carbides is approximately 16.5%.

[0112] The above-mentioned Ni3Al / carbide composite powder was used to perform laser cladding on the surface of 42CrMo steel. The laser power was 2000W, the scanning speed was 0.18m / min, the laser rectangular spot size was 5mm×2mm, and the coaxial powder feeding rate was 17.5g / min, forming an in-situ self-generated carbide reinforced Ni3Al-based alloy strengthening layer.

[0113] The in-situ self-generated carbide-reinforced Ni3Al-based alloy strengthening layer prepared in this comparative example was crack-free and exhibited uniform carbide distribution. However, the average hardness of the Ni3Al-based alloy strengthening layer was relatively low, at 546 HV. Under dry friction conditions (surface friction, with gray cast iron as the grinding material), the wear rate of the Ni3Al-based alloy strengthening layer was 1.19 × 10⁻⁶. -5 mm 3 The wear rate of the grinding material, gray cast iron, is 3.05 × 10⁶ N·m. -5 mm 3 / (N·m).

[0114] Compared with Example 1, the hardness and wear resistance of the reinforced layer in this comparative example are lower.

[0115] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A high-temperature impact and wear resistant reinforcing layer, characterized in that, The high-temperature impact and wear resistant reinforcement layer is prepared using alloy powder with high carbide content. The chemical composition of the alloy powder with high carbide content, by mass percentage, is: Al: 2.7%~3.0%, C: 5.8%~6.3%, Cr: 63.5%~64.5%, B: 0.02%~0.04%, O≤200ppm, N≤50ppm, H≤5ppm, with the balance being Ni. The ratio of nickel equivalent to aluminum equivalent in the high carbide content alloy powder is 3.2 to 3.

5. The principle for calculating the number of nickel equivalent atoms is as follows: Where Ni represents the mass percentage of Ni element in the alloy powder with high carbide content, and Cr... Ni3Al溶 It ranges from 3% to 7%; The principle for calculating the equivalent atomic number of aluminum is as follows: The microstructure of the high carbide content alloy powder includes Ni3Al phase, a small amount of γ-Ni phase and carbides. The structure of the carbides mainly includes Cr7C3, and the mass content of the carbides is 63%~67%. The mass content of the γ-Ni phase is 2.0%~5.0%. The carbides are dispersed and the length of the carbides is 10μm~20μm. After the high-temperature impact and wear resistant reinforcing layer is applied to the valve seat bore of the diesel engine cylinder head, the average hardness of the reinforcing layer is 1000~1200HV, and the wear rate is ≤0.6×10⁻⁶. -5 mm 3 The shear strength of the interface between the reinforced layer and the cylinder head substrate is 400~500MPa, and the average oxidation rate at 1000℃ is ≤0.06g / m. 2 •h.

2. The high-temperature impact and wear resistant reinforcing layer according to claim 1, characterized in that, In the microstructure of the alloy powder with high carbide content, the mass content of the carbides is 63%~65%.

3. The high-temperature impact and wear resistant reinforcing layer according to claim 1, characterized in that, The ratio of nickel equivalent to aluminum equivalent in the alloy powder with high carbide content is 3.24 to 3.

5.

4. The high-temperature impact and wear resistant reinforcing layer according to claim 1, characterized in that, The alloy powder with high carbide content has the following chemical composition by mass percentage: Al: 2.75%~2.95%, C: 5.82%~6.28%, Cr: 63.5%~64.5%, B: 0.02%~0.035%, O≤190ppm, N≤45ppm, H≤5ppm, with the balance being Ni.

5. A method for preparing a high-temperature impact and wear resistant reinforcing layer according to any one of claims 1 to 4, characterized in that, Includes the following steps: Step 1: High carbide content alloy powder is conveyed to the substrate surface using a coaxial powder feeding method; Step 2: Use laser cladding to clad alloy powder with high carbide content onto the substrate surface to form a reinforcing layer.

6. The preparation method according to claim 5, characterized in that, In step 1, the particle size range of the intermetallic compound alloy powder with high carbide content is controlled to be 53 μm to 124 μm.

7. The preparation method according to claim 5, characterized in that, In step 1, the coaxial powder feeding rate is controlled to be 10g / min~20g / min.

8. The preparation method according to claim 5, characterized in that, In step 2, the power of the laser cladding is controlled to be 2200W~2400W, and the scanning speed is 0.36m / min~0.60m / min.

9. An application of a high-temperature impact and wear resistant reinforcing layer, characterized in that, The high-temperature impact and wear resistant reinforcing layer according to any one of claims 1 to 4 or the high-temperature impact and wear resistant reinforcing layer prepared by the preparation method according to any one of claims 5 to 8 is used for surface modification of diesel engine components.

10. A diesel engine cylinder head, characterized in that, The valve seat bore of the diesel engine cylinder head includes the high-temperature impact and wear resistant reinforcing layer as described in any one of claims 1 to 4, or the high-temperature impact and wear resistant reinforcing layer prepared by the preparation method described in any one of claims 5 to 8.

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